Risk Factors and Mortality Among Women With Interval Breast Cancer vs Screen-Detected Breast Cancer.

Importance: The risk factors for interval breast cancer (IBC) compared with those for screen-detected breast cancer (SBC) and their association with mortality outcomes have not yet been evaluated among Korean women. Objective: To evaluate risk factors associated with IBC and survival among Korean women with IBC compared with those with SBC. Design, Setting, and Participants: This retrospective cohort study used data from the Korean National Health Insurance Service Database. Women who participated in a national mammographic breast cancer screening program between January 1, 2009, and December 31, 2012, were included. Mortality outcomes were calculated from the date of breast cancer diagnosis to the date of death or December 31, 2020. Data were analyzed from March 1 to June 30, 2023. Exposure: Breast cancer diagnosed within 6 to 24 months after a negative screening result (ie, IBC) or within 6 months after a positive screening result (ie, SBC). Main Outcomes and Measures: Risk factors and survival rates for IBC and SBC. Results: This study included 8702 women with IBC (mean [SD] age, 53.3 [8.6] years) and 9492 women with SBC (mean [SD] age, 54.1 [9.0] years). Compared with SBC, the probability of IBC decreased as mammographic density increased. Lower body mass index, menopausal status, hormone replacement therapy (HRT) use, and lack of family history of breast cancer were associated with a higher likelihood of IBC. When stratified by detection time, younger age at breast cancer diagnosis and family history of breast cancer were associated with an increased likelihood of IBC diagnosed at 6 to 12 months but a decreased likelihood of IBC diagnosed at 12 to 24 months. Overall mortality of IBC was comparable with SBC, but total mortality and cancer-related mortality of IBC diagnosed between 6 and 12 months was higher than that of SBC. Conclusions and Relevance: The findings of this cohort study suggest that breast density, obesity, and HRT use were associated with IBC compared with SBC. These findings also suggest that higher supplemental breast ultrasound use among Korean women, especially those with dense breasts, could be attributed to a lower incidence of IBC among women with dense breasts compared with women with SBC, due to greater detection. Finally, overall mortality of IBC was comparable with that of SBC.

Associations between breast cancer risk factors and mammographic breast density in a large cross-section of Korean women.

BACKGROUND: We investigated the association between established risk factors for breast cancer and mammographic breast density in Korean women. METHODS: This large cross-sectional study included 8 460 928 women aged >40 years, who were screened for breast cancer between 2009 and 2018. Breast density was assessed using the Breast Imaging Reporting and Data System. This study used multiple logistic regression analyses of age, BMI, age at menarche, menopausal status, menopausal age, parity, breastfeeding status, oral contraceptive use, family history of breast cancer, physical activity, smoking, drinking and hormone replacement therapy use to investigate their associations with mammographic breast density. Analyses were performed using SAS software. RESULTS: Of 8 460 928 women, 4 139 869 (48.9%) had nondense breasts and 4 321 059 (51.1%) had dense breasts. Factors associated with dense breasts were: earlier age at menarche [<15 vs. ≥15; adjusted odds ratio (aOR), 1.18; 95% confidence interval (CI), 1.17-1.18], premenopausal status (aOR, 2.01; 95% CI, 2.00-2.02), later age at menopause (≥52 vs. <52; aOR, 1.23; 95% CI, 1.22-1.23), nulliparity (aOR, 1.64; 95% CI, 1.63-1.65), never breastfed (aOR, 1.23; 95% CI, 1.23-1.24) and use of hormone replacement therapy (aOR, 1.29; 95% CI, 1.28-1.29). Women with a higher BMI and the use of oral contraceptives were more likely to have nondense breasts. CONCLUSION: Lower BMI, reproductive health and behavioral factors were associated with dense breasts in Korean women. Additional research should investigate the relationship between mammographic breast density, breast cancer risk factors and breast cancer risk.

Longitudinal Changes in Smoking Behaviors and Cancer-Related Mortality Risk in Middle-Aged Korean Women.

PURPOSE: This study investigated association between smoking habit change and cancer-related mortality risk in Korean women. MATERIALS AND METHODS: Study population were women aged ≥ 40 years who underwent two biennial cancer screenings during 2009-2012 and were followed up until 2020. Participants were grouped into sustained nonsmokers, sustained quitters, new quitters, relapsers/smoking initiators, and sustained smokers. Outcomes included all-cause and cancer-related deaths. Cox regression and competing risk analysis was used to assess association between smoking habit change and mortality risk. RESULTS: Of 2,892,590 women, 54,443 death cases were recorded (median follow-up of 9.0 years). Compared with sustained nonsmokers, mortality risk from all causes and cancer-related causes increased in all other smoking groups. Cancer-related risk increased 1.22-fold among sustained quitters (95% confidence interval [CI], 1.10 to 1.36), 1.56-fold (95% CI, 1.40 to 1.75) in new quitters, 1.40-fold (95% CI, 1.21 to 1.62) in relapsers/smoking initiators, and 1.61-fold (95% CI, 1.46 to 1.78) in sustained smokers compared with sustained nonsmokers. Women who were sustained smokers with higher smoking intensity had a higher mortality risk in terms of hazard ratios compared to nonsmokers (< 5 pack-years 2.12-fold, 5-10 pack-years 2.15-fold, and > 10 pack-years 2.27-fold). CONCLUSION: Quitting smoking earlier is critical for preventing death from all causes and cancer among female smokers.

Temporal Trend in Uptake of the National General Health Checkups and Cancer Screening Program among Korean Women with Breast Cancer.

PURPOSE: This study assessed the temporal trends of uptake of national general health and cancer screening among women with breast cancer in Korea between 2009 and 2016. MATERIALS AND METHODS: We retrospectively analyzed the claims data from the Korean National Health Insurance Service database. Participants included 101,403 breast cancer patients diagnosed between 2009 and 2016. Information on participation in national screening programs, including breast cancer screening, general health, and gastric, colorectal, and cervical cancers, up to 2020 was collected. Screening participation rates within the first 2 and 5 years postdiagnosis were calculated by diagnosis year and fitted with joinpoint regression models to assess temporal trends. RESULTS: Overall, the participation rate in breast cancer screening within 2 years postdiagnosis increased from 10.9% to 14.0% from 2009-2016, with an annual percentage change (APC) of 3.7% (p < 0.05). The participation rate in breast cancer screening was lower than that in general health checkup and screening for other cancers within 2 and 5 years postdiagnosis. A steady increase in screening trends was also observed for general health, gastric, colorectal, and cervical cancers, with APC of 5.3%, 5.7%, 6.9%, and 7.6% in the 2-year postdiagnosis rate, and APC of 3.6%, 3.7%, 3.7%, and 4.4% in 5-year postdiagnosis rate, respectively. The screening rate was highest among age groups 50-59 and 60-69 in 2009 and significant upward trends were observed in all age groups for general health checkup and gastric, colorectal, and cervical cancer screening. CONCLUSION: Among female breast cancer survivors in Korea, the uptake rate of screenings for general health and various cancers, including breast, gastric, colorectal, and cervical cancers, has shown a gradual increase in recent years.

Mammographic breast density and cardiovascular disease risk in women.

AIMS: We aimed to determine the predictive role of mammographic breast density in addition to the Framingham Risk Score (FRS) on subsequent CVD events in women. METHODS AND RESULTS: This cohort study included 4,268,579 women aged ≥40 years who underwent mammography screening between 2009 and 2010 with follow-up until 2020. Breast density was reported following the Breast Imaging Reporting and Data System. Primary outcomes included coronary heart disease, cerebrovascular disease, peripheral arterial disease, and heart failure. The incremental predictive ability of breast density added to the FRS model was assessed using the ROC and net reclassification index (NRI) among all women and strata based on FRS risk categories (<5% as low-risk, 5%-10% as moderate-risk, and ≥10% as high-risk). In total, 135,475 CVD events were recorded after a median follow-up of 10.9 years. A lower category of breast density was associated with a higher risk of CVD. Compared to the extremely dense breast group, the hazard ratios (95% CI) for CVDs were 1.12 (1.09-1.14), 1.19 (1.17-1.22), and 1.29 (1.26-1.32) in women with heterogeneously dense, scattered fibroglandular densities, and almost entirely fat breast density, respectively. Adding breast density to the FRS showed a slight improvement in AUROC but a modest improvement in NRI; the C-statistic difference was 0.083% (95% CI 0.069-0.096) with a 7.15% (6.85-7.69) increase in NRI, with the strongest improvement observed in the low-risk group. CONCLUSIONS: Mammographic breast density is an independent predictor of incident CVD among women. The addition of mammographic breast density to FRS improves the prediction of CVDs, especially in low-risk individuals.

Mammographic Breast Density and Risk of Ovarian Cancer in Korean Women.

BACKGROUND: This study aimed to investigate the potential association between mammographic breast density and ovarian cancer risk. METHODS: This retrospective cohort study included women ≥40 years of age who underwent a mammography screening from 2009 to 2014. Breast density was assessed using the Breast Imaging-Reporting and Data System. The primary outcome was ovarian cancer development, and the cases were recorded until 2020. Cox proportional hazards regression was used to assess the association between breast density and ovarian cancer development. Subgroup analyses stratified by age, menopausal status, and body mass index (BMI) were conducted. RESULTS: Of the 8,556,914 women included in this study, 9,246 ovarian cancer events were recorded during a median follow-up period of 10 years (interquartile range, 8.1-11.0 years). Compared with women with almost entirely fat density, those with scattered fibroglandular density, heterogeneous density, and extreme density had an increased risk of ovarian cancer with adjusted HRs of 1.08 [95% confidence interval (CI), 1.02-1.15], 1.16 (95% CI, 1.09-1.24), and 1.24 (95% CI, 1.15-1.34), respectively. The strongest association was observed in the ≥60 years age group; subgroup analysis indicated a significant increase in association between the higher-density category and ovarian cancer risk, regardless of BMI or menopausal status. CONCLUSIONS: Higher levels of breast density are associated with an increased risk of ovarian cancer. IMPACT: Breast density may have a relationship with ovarian cancer risk and could be used to assess future risk.

Trends for syndromic surveillance of norovirus in emergency department data based on chief complaints.

BACKGROUND: This study compared the trends in norovirus cases to determine whether chief complaint-based emergency department (ED) visits data could reflect trends of norovirus in Korea. METHODS: The ED visits from the National Emergency Department Information System (NEDIS) database and the weekly reported number of noroviruses from the sentinel surveillance system were collected between August 2017 and December 2020. The correlation between weekly norovirus cases and weekly ED visits considering the chief complaint and discharge diagnosis code was estimated using a three-week moving average. RESULTS: In total, 6,399,774 patients with chief complaints of digestive system disease visited ED. A higher correlation between reported norovirus cases and ED visit with chief complaint of vomiting and discharge diagnosis code of gastroenteritis and colitis of unspecified origin or other and unspecified gastroenteritis and colitis of infectious origin was observed (R=0.88, p<.0001). The correlation was highest for the 0-4-years age group (R=0.89, p<.0001). However, no correlation was observed between the reported norovirus cases and the number of emergency department visits with norovirus identified as a discharge diagnosis code. CONCLUSIONS: ED visit data considering a combination of chief complaints and discharged diagnosis code would be available for early detection of infectious disease trends.

Increased risk of cancer and cancer-related mortality in middle-aged Korean women with prediabetes and diabetes: a population-based study.

OBJECTIVES: This study investigated the risk of developing and dying from all types of cancer, as well as cancer-specific mortality, in women diagnosed with prediabetes and diabetes. METHODS: We included women aged ≥40 years who underwent cancer screening from 2009 to 2014 with follow-up until 2020. Diabetes status was determined based on fasting plasma glucose levels, self-reported history of diabetes, and the use of antidiabetic medication. We quantified the risk of cancer and mortality in the prediabetes and diabetes groups, relative to the normoglycemia group, by calculating adjusted hazard ratios (aHRs). RESULTS: The study included 8,309,393 participants with a mean age of 52.7±9.7 years. Among these participants, 522,894 cases of cancer and 193,283 deaths were detected. An increased risk of cancer was observed in both the prediabetes group (aHR, 1.03; 95% confidence interval [CI], 1.02 to 1.04) and the diabetes group (aHR, 1.13; 95% CI, 1.12 to 1.14). The highest risk was identified in those with diabetes who developed liver (aHR, 1.72; 95% CI, 1.66 to 1.79), pancreatic (aHR, 1.68; 95% CI, 1.60 to 1.76), and gallbladder cancer (aHR, 1.43; 95% CI, 1.36 to 1.51). Women with prediabetes and diabetes exhibited a 1.07-fold (95% CI, 1.05 to 1.08) and 1.38-fold (95% CI, 1.36 to 1.41) increased risk of death from cancer, respectively. CONCLUSIONS: Both prediabetes and diabetes were associated with an elevated risk of cancer, as well as an increased risk of death from cancer, in middle-aged Korean women. However, the degree of risk varied depending on the specific site of the cancer.

Changes in metabolic syndrome and the risk of breast and endometrial cancer according to menopause in Korean women.

OBJECTIVES: This study investigated how changes in metabolic syndrome (MetS) are associated with the subsequent risk of breast and endometrial cancer according to menopausal status. METHODS: This cohort study, using data from the National Health Insurance Service database, included women aged ≥40 years who underwent 2 biennial cancer screenings (2009-2010 and 2011-2012) and were followed up until 2020. Participants were grouped into MetS-free, MetS-recovery, MetS-development, and MetS-persistent groups. Menopausal status (premenopausal, perimenopausal, and postmenopausal) was assessed at 2 screenings. Cox proportional hazard regression was used to assess the association between MetS changes and cancer risk. RESULTS: In 3,031,980 women, breast and endometrial cancers were detected in 39,184 and 4,298, respectively. Compared with the MetS-free group, those who recovered, developed, or had persistent MetS showed an increased risk of breast cancer, with adjusted hazard ratios (aHRs) of 1.05, 1.05, and 1.11, respectively (p<0.005). MetS persistence was associated with an increased risk of breast cancer in postmenopausal women (aHR, 1.12, 95% confidence interval [CI], 1.08 to 1.16) but not in premenopausal or perimenopausal women. MetS persistence was associated with an increased risk of endometrial cancer in premenopausal, perimenopausal, and postmenopausal women, with aHRs of 1.41 (95% CI, 1.17 to 1.70), 1.59 (95% CI, 1.19 to 2.12), and 1.47 (95% CI, 1.32 to 1.63), respectively. CONCLUSIONS: Increased breast cancer risk was associated with recovered, developed, and persistent MetS in postmenopausal women. Meanwhile, increased endometrial cancer risk was found in obese women who recovered from MetS or persistently had MetS, regardless of menopausal status, when compared to MetS-free women.

Association of Breast Cancer Family History With Breast Density Over Time in Korean Women.

Importance: Evidence suggests that women with a family history of breast cancer (FHBC) in first-degree relatives have a higher level of breast density; however, studies of premenopausal women remain limited. Objective: To investigate the association between FHBC and mammographic breast density and breast density changes among premenopausal women. Design, Setting, and Participants: This retrospective cohort study used population-based data obtained from the National Health Insurance Service-National Health Information Database of Korea. We included premenopausal women aged 40 to 55 years who underwent mammography for breast cancer screening once between January 1, 2015, and December 31, 2016 (n = 1 174 214), and women who underwent mammography twice (first in 2015-2016 and again between January 1, 2017 and December 31, 2018) (n = 838 855). Exposures: Family history of breast cancer was assessed using a self-reported questionnaire, which included information on FHBC in the mother and/or sister. Main Outcomes and Measures: Breast density, based on the Breast Imaging Reporting and Data System, was categorized as dense (heterogeneously or extremely dense) and nondense (almost entirely fat or scattered fibroglandular areas). Multivariate logistic regression was used to assess the association among FHBC, breast density, and changes in breast density from the first to second screening. Data analysis was performed from June 1 to September 31, 2022. Results: Of the 1 174 214 premenopausal women, 34 003 (2.4%; mean [SD] age, 46.3 [3.2] years) reported having FHBC among their first-degree relatives, and 1 140 211 (97.1%; mean [SD] age, 46.3 [3.2] years) reported no FHBC. Odds of having dense breasts was 22% higher (adjusted odds ratio [aOR], 1.22; 95% CI, 1.19-1.26) in women with FHBC than in women without FHBC, and the association varied by affected relatives: mother alone (aOR, 1.15; 95% CI, 1.10-1.21), sister alone (aOR, 1.26; 95% CI, 1.22-1.31), and both mother and sister (aOR, 1.64; 95% CI, 1.20-2.25). Among women with fatty breasts at baseline, the odds of developing dense breasts was higher in women with FHBC than in those without FHBC (aOR, 1.19; 95% CI, 1.11-1.26), whereas among women with dense breasts, higher odds of having persistently dense breasts were observed in women with FHBC (aOR, 1.11; 95% CI, 1.05-1.16) than in those without FHBC. Conclusions and Relevance: In this cohort study of premenopausal Korean women, FHBC was positively associated with an increased incidence of having increased or persistently dense breasts over time. These findings suggest the need for a tailored breast cancer risk assessment for women with FHBC.

Association of Longitudinal Mammographic Breast Density Changes with Subsequent Breast Cancer Risk.

Background Although Breast Imaging Reporting and Data System (BI-RADS) density classification has been used to assess future breast cancer risk, its reliability and validity are still debated in literature. Purpose To determine the association between overall longitudinal changes in mammographic breast density and breast cancer risk stratified by menopausal status. Materials and Methods In a retrospective cohort study using the Korean National Health Insurance Service database, women aged at least 40 years without a history of cancer who underwent three consecutive biennial mammographic screenings in 2009-2014 were followed up through December 2020. Participants were divided according to baseline breast density: fatty (BI-RADS categories a, b) versus dense (BI-RADS categories c, d) and then into subgroups on the basis of changes from the first to second and from second to third screenings. Women without change in breast density were used as the reference group. Main outcomes were incident breast cancer events, both invasive breast cancer and ductal carcinoma in situ. Cox proportion hazard regression was used to calculate the hazard ratio (HR) with adjustment for other covariables. Results Among 2 253 963 women (mean age, 59 years ± 9) there were 22 439 detected breast cancers. Premenopausal women with fatty breasts at the first screening had a higher risk of breast cancer as density increased in the second and third screenings (fatty-to-dense HR, 1.45 [95% CI: 1.27, 1.65]; dense-to-fatty HR, 1.53 [95% CI: 1.34, 1.74]; dense-to-dense HR, 1.93 [95% CI: 1.75, 2.13]). In premenopausal women with dense breasts at baseline, those in whom density continuously decreased had a 0.62-fold lower risk (95% CI: 0.56, 0.69). Similar results were observed in postmenopausal women, remaining significant after adjustment for baseline breast density or changes in body mass index (fatty-to-dense HR, 1.50 [95% CI: 1.39, 1.62]; dense-to-fatty HR, 1.42 [95% CI: 1.31, 1.53]; dense-to-dense HR, 1.62 [95% CI: 1.51, 1.75]). Conclusion In both premenopausal and postmenopausal women undergoing three consecutive biennial mammographic screenings, a consecutive increase in breast density augmented the future breast cancer risk whereas a continuous decrease was associated with a lower risk. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Kataoka et al in this issue.

Microcalcifications, mammographic breast density, and risk of breast cancer: a cohort study.

BACKGROUND: Breast density and microcalcifications are strongly associated with the risk of breast cancer. However, few studies have evaluated the combined association between these two factors and breast cancer risk. We investigated the association between breast density, microcalcifications, and risk of breast cancer. METHODS: This cohort study included 3,910,815 women aged 40-74 years who were screened for breast cancer between 2009 and 2010 and followed up until 2020. The National Health Insurance Service database includes national health-screening results from the national breast cancer screening program, which is an organized screening program provided every 2 years for all women aged 40 years or older. Breast density was assessed based on the Breast Imaging Reporting and Data System (BI-RADS) 4th edition, mostly through visual assessment by radiologists. The presence or absence of microcalcifications was obtained from the mammographic results. Cox proportional hazard regression for breast cancer risk was used to estimate hazard ratios (aHRs) adjusted for breast cancer risk factors. RESULTS: A total of 58,315 women developed breast cancer during a median follow-up of 10.8 years. Women with breast cancer had a higher proportion of microcalcifications than women without breast cancer (0.9% vs. 0.3%). After adjusting for breast density, women with microcalcification had a 3.07-fold (95% confidence interval [CI] 2.82-3.35) increased risk of breast cancer compared to women without microcalcification. The combined association between microcalcification and breast density dramatically increased the risk of breast cancer, corresponding to a higher level of breast density. Among postmenopausal women, the highest risk group was women with BI-RADS 4 and microcalcification. These women had more than a sevenfold higher risk than women with BI-RADS 1 and non-microcalcification (aHR, 7.26; 95% CI 5.01-10.53). CONCLUSION: Microcalcification is an independent risk factor for breast cancer, and its risk is elevated when combined with breast density.

Longitudinal Changes in Smoking Habits in Women and Subsequent Risk of Cancer.

INTRODUCTION: This study investigated the association between longitudinal smoking habit changes and cancer risk in a cohort of Korean women. METHODS: Study population included women aged ≥40 years who underwent 2 biennial cancer screenings (2009-2010 and 2011-2012) and were followed up until 2020. This analysis was conducted in 2021. On the basis of changes in smoking habits, participants were grouped into sustained nonsmokers, sustained quitters, new quitters, relapsers, smoking initiators, and sustained smokers. Outcomes included incident cancer cases, smoking-related cancers, and specific cancer sites. RESULTS: Of 3,051,946 women, the mean age was 54.8 years, and the median follow-up was 8.9 years. Compared with sustained nonsmokers, other groups had a significantly increased risk of cancer and smoking-related cancers: sustained quitters (adjusted hazard ratio=1.05; 95% CI=1.01, 1.09), new quitters (adjusted hazard ratio=1.12; 95% CI=1.07, 1.17), and sustained smokers (adjusted hazard ratio=1.14; 95% CI=1.09, 1.19). A significantly increased risk of lung, stomach, liver, and pancreas cancers was found in sustained smokers and new quitters. Relapsers/smoking initiators showed a higher risk of liver, lung, and breast cancer than sustained nonsmokers, but the strength of their corresponding adjusted hazard ratio was generally lower than that of sustained smokers. The hazard ratio of cancer risk was 0.92 (95% CI=0.87, 0.97) among sustained quitters and 0.97 (95% CI=0.91, 1.03) among new quitters relative to that among sustained smokers. CONCLUSIONS: This study found a significant association between changes in smoking behavior and cancer risk. These findings suggest that smoking cessation is critical for cancer prevention in women.

Family history of breast cancer, mammographic breast density and breast cancer risk: Findings from a cohort study of Korean women.

BACKGROUND: This study investigated whether the association between family history of breast cancer in first-degree relatives and breast cancer risk varies by breast density. METHODS: Women aged 40 years and older who underwent screening between 2009 and 2010 were followed up until 2020. Family history was assessed using a self-reported questionnaire. Using Breast Imaging Reporting and Data System (BI-RADS), breast density was categorized into dense breast (heterogeneously or extremely dense) and non-dense breast (almost entirely fatty or scattered areas of fibro-glandular). Cox regression model was used to assess the association between family history and breast cancer risk. RESULTS: Of the 4,835,507 women, 79,153 (1.6%) reported having a family history of breast cancer and 77,238 women developed breast cancer. Family history led to an increase in the 5-year cumulative incidence in women with dense- and non-dense breasts. Results from the regression model with and without adjustment for breast density yielded similar HRs in all age groups, suggesting that breast density did not modify the association between family history and breast cancer. After adjusting for breast density and other factors, family history of breast cancer was associated with an increased risk of breast cancer in all three age groups (age 40-49 years: aHR 1.96, 95% confidence interval [CI] 1.85-2.08; age 50-64 years: aHR 1.70, 95% CI 1.58-1.82, and age ≥65 years: aHR 1.95, 95% CI 1.78-2.14). CONCLUSION: Family history of breast cancer and breast density are independently associated with breast cancer. Both factors should be carefully considered in future risk prediction models of breast cancer.

Consecutive gain and loss in body weight and waist circumference with risk of subsequent breast cancer in Korean women.

BACKGROUND: This study investigated the association between longitudinal changes in weight and waist circumference and breast cancer risk according to menopausal status. METHODS: This retrospective cohort study used data from the population-based Korean National Health Insurance Service (NHI) database. The study population included women aged ≥40 years who consecutively underwent three biennial breast cancer screenings between 2009-2014 and were followed up until 2020. The percentage changes in weight and waist circumference during the three screenings were calculated and categorized into five groups based on the level of increase or decrease in these two factors. Hazard ratios (HRs) and 95% confidence intervals (95% CI) for breast cancer risk were calculated and adjusted for other factors. RESULTS: Of 691,253 premenopausal and 1,519,211 postmenopausal women, 9485 and 12,553 breast cancer cases were identified, respectively, during a median 6.9 follow-up years. Postmenopausal women with two consecutive weight gains had an increased risk of breast cancer risk (HR = 1.11, 95% CI = 1.01 to 1.22); meanwhile, consecutive weight loss was associated with a decreased risk (HR = 0.84, 95% CI = 0.76 to 0.93). Single time and continuous decreases in waist circumference were associated with a decreased risk (HR = 0.91, 95% CI = 0.85 to 0.98, and HR = 0.84, 95% CI = 0.76-0.93), while single time and continuous increases were associated with an increased risk (HR = 1.08, 95% CI = 1.01 to 1.15, and HR = 1.13, 95% CI = 1.04 to 1.22). Single weight gain was associated with the increased breast cancer risk in premenopausal women (HR = 1.07, 95% CI = 1.01 1.13). CONCLUSIONS: Our findings suggest a dose-response relationship between weight, waist circumference change, and the risk of future breast cancer.

Mammographic Breast Density, Benign Breast Disease, and Subsequent Breast Cancer Risk in 3.9 Million Korean Women.

Background Mammographic breast density and benign breast disease are strong risk factors for breast cancer. Accordingly, women with both risk factors may have a markedly high risk for developing breast cancer. Purpose To investigate the risk of breast cancer associated with the combination of mammographic density and benign breast disease in Korean women, where population-based mammographic breast cancer screening is provided for all women aged at least 40 years. Materials and Methods This is a retrospective analysis of data from a nationwide breast cancer screening program linked with the national cancer registry. The study included Korean women between 40-74 years of age screened for breast cancer between January 2009 and December 2010 and observed up to December 2020 (median follow-up of 10.6 years). Benign breast disease and breast density were extracted from mammography screening results. Cox proportional hazard regression analysis was used to calculate adjusted hazard ratios (HRs) for breast cancer risk. Results In this study, 3 911 348 women (mean age, 53 years ± 9 [SD]) were analyzed. During follow-up (median, 10.6 years), 58 321 women developed breast cancer. At screening, 10 729 (18.4%) cases of benign breast disease were detected among women who developed breast cancer. Women with extremely dense breasts (Breast Imaging Reporting and Data System [BI-RADS] density category D) and benign breast disease had a greater risk of breast cancer when compared with women presenting with fatty breast (BI-RADS density category A) and those without benign breast disease (HR, 2.75; 95% CI: 2.63, 2.88; P < .001). Women with benign breast disease and fatty breasts (HR, 1.49; 95% CI: 1.40, 1.58; P < .001) and women with extremely dense breasts and without benign breast disease (HR, 2.28; 95% CI: 2.20, 2.35; P < .001) also had an elevated breast cancer risk compared with women with fatty breast tissue. Conclusion Women with dense breasts and benign breast disease at screening mammography had an elevated risk of future breast cancer. © RSNA, 2022 Online supplemental material is available for this article.

Mammographic breast density, body mass index and risk of breast cancer in Korean women aged 75 years and older.

Mammographic breast density and body mass index (BMI) are strong risk factors of breast cancer, but few studies have investigated these factors in older women. Our study assessed the association between breast density, BMI and the breast cancer risk among women aged ≥75 years. We included women who underwent breast cancer screening between 2009 and 2014 and were followed up until 2020. Breast density was measured using Breast Imaging Reporting and Data System. BMI was classified into three groups: <23, 23 to <25 and ≥25. Cox proportional hazards models were used to estimate the association of breast density and BMI with breast cancer risk. In 483 564 women, 1885 developed breast cancer. The 5-year incidence increased with an increase in breast density and BMI. Increase in breast density was associated with an increased breast cancer risk in all BMI categories: among women with BMI <23, those with heterogeneous/extreme density had a 2.98-fold (95% CI: 2.23-3.80) increased risk of breast cancer compared to those with entirely fatty breasts. An increase in BMI was associated with increased breast cancer risk in women with the same breast density in all density categories. When the combined associations of breast density and BMI on the risk of breast cancer were considered, women with a BMI ≥25 and heterogeneous/extreme breast density had a 5.35-fold (95% CI: 4.26-6.72) increased risk of breast cancer compared to women with a BMI <23 and fatty breasts. Women aged ≥75 years, with dense breasts, regardless of BMI status, might benefit from a tailored screening strategy for early detection of breast cancer.

Trends in gastrointestinal infections before and during non-pharmaceutical interventions in Korea in comparison with the United States.

OBJECTIVES: This study examined how trends in the weekly frequencies of gastrointestinal infectious diseases changed before and during the coronavirus disease 2019 (COVID-19) pandemic in Korea, and compared them with the trends in the United States. METHODS: We compared the weekly frequencies of gastrointestinal infectious diseases (16 bacterial and 6 viral diseases) in Korea during weeks 5-52 before and after COVID-19. In addition, the weekly frequencies of 5 gastrointestinal infectious diseases in the United States (data from the Centers for Disease Control and Prevention) that overlapped with those in Korea were compared. RESULTS: The mean weekly number of total cases of gastrointestinal infectious diseases in Korea showed a significant decrease (from 522 before COVID-19 to 245 after COVID-19, p<0.01). Only bacterial gastrointestinal infectious diseases caused by Campylobacter increased significantly; other bacterial gastrointestinal infectious diseases showed either a decrease or no change. The incidence of all other viral diseases decreased. In the United States, the weekly numbers of Salmonella, Campylobacter, typhoid, shigellosis, and hepatitis A virus cases sharply decreased after the COVID-19 outbreak. The weekly case numbers of all viral diseases markedly decreased in both countries; however, bacterial gastrointestinal infectious diseases showed a different pattern. CONCLUSIONS: The incidence of gastrointestinal infectious diseases decreased after the COVID-19 outbreak. In contrast, Campylobacter infections showed an increasing trend in Korea, but a decreasing trend in the United States. Further studies are needed to elucidate the different trends in bacterial and viral infectious diseases before and after non-pharmaceutical interventions and between different countries.

Association of the Interaction Between Mammographic Breast Density, Body Mass Index, and Menopausal Status With Breast Cancer Risk Among Korean Women.

Importance: Evidence suggests that breast density and body mass index (BMI) are strong breast cancer risk factors; however, their interactive associations are unknown. Elucidation of these interactive associations may help to increase understanding of the causes of breast cancer and find effective interventions for susceptible subgroups. Objective: To explore the association of the interaction of mammographic breast density and BMI with breast cancer risks among premenopausal and postmenopausal women. Design, Setting, and Participants: This prospective observational cohort study used population-based data of the Korean National Cancer Screening Program embedded in the National Health Insurance Service database to evaluate the breast cancer risk of 3 248 941 premenopausal cancer-free women and 4 373 473 postmenopausal cancer-free women aged 40 years or older who underwent mammographic screening between January 1, 2009, and December 31, 2013, and were followed up until December 31, 2018. Statistical analysis was performed from June 1 to July 15, 2021. Exposures: Breast Imaging Reporting and Data System (BI-RADS)-defined breast density (with a scale from 1 to 4, where 1 indicates almost entirely fat, 2 indicates scattered fibroglandular densities, 3 indicates heterogeneously dense tissue, and 4 indicates extremely dense tissue) and BMI levels classified according to the World Health Organization Asia-Pacific Region classification. Main Outcomes and Measures: Adjusted relative risk (aRR) of breast cancer during the follow-up period and interactions in additive and multiplicative scales. The study end point was the development of breast cancer. Results: Of 3 248 941 premenopausal women (mean [SD] age, 44.6 [4.3] years) and 4 373 473 postmenopausal women (mean [SD] age, 59.6 [8.4] years) aged 40 years or older, 34 466 cases of breast cancer were identified among the premenopausal women, and 30 816 cases of breast cancer were identified among the postmenopausal women. Increased breast density was associated with an increased risk of breast cancer in both premenopausal and postmenopausal women across the BMI categories. Among premenopausal women, those in BI-RADS category 4 had an approximately 2-fold higher risk of breast cancer irrespective of BMI (all women: aRR, 2.36 [95% CI, 2.24-2.49]; underweight: aRR, 1.80 [95% CI, 1.25-2.59]; normal weight: aRR, 2.10 [95% CI, 1.93-2.28]; overweight: aRR, 2.47 [95% CI, 2.27-2.68]; obese: aRR, 2.87 [95% CI, 2.49-3.32]) than those with underweight status and in BI-RADS category 1. However, an association between BMI and the risk of breast cancer was found only in the postmenopausal women in all breast density categories compared with underweight women with BI-RADS category 1 (BI-RADS category 4, all women: aRR, 2.91 [95% CI, 2.78-3.04]; underweight: aRR, 2.74 [95% CI, 1.89-3.98]; normal weight: aRR, 3.05 [95% CI, 2.82-3.30]; overweight: aRR, 2.85 [95% CI, 2.67-3.04]; obese: aRR, 2.52 [95% CI, 2.22-2.88]). When the combined associations of breast density and BMI with the risk of breast cancer were considered, a high breast density and high BMI had a significant positive interaction on the additive scale for both premenopausal and postmenopausal women, especially the latter (premenopausal women: adjusted relative excess risk due to interaction, 0.53 [95% CI, 0.35-0.71]; postmenopausal women: adjusted relative excess risk due to interaction, 1.68 [95% CI, 1.26-2.10]). Conclusions and Relevance: This study suggests that breast density and BMI interact synergistically to augment breast cancer risk, with a stronger association found among postmenopausal women. Both factors should be incorporated into risk stratification in a population-based screening for public health significance. Women with overweight or obesity and dense breast tissue might benefit from tailored early screening strategies to detect breast cancer.